Field
Device discovery may be important in a variety of communication systems including, for example, wireless communication systems. Thus, certain embodiments may provide a device to device beacon design that may provide for efficient interference management and resource allocation.
Description of the Related Art
Direct device-to-device (D2D) is an area that may, in third generation partnership project (3GPP) release 12 (Rel-12), include features such as long term evolution (LTE) D2D discovery and communication. Discovery and communication may be two independent procedures. 3GPP technical report (TR) 22.803 (which is hereby incorporated herein by reference in its entirety) defines a proximity service (ProSe)-enabled UE as “a UE that supports ProSe Discovery and/or ProSe Communication,” although any user equipment configured to operate in connection with ProSe may be considered ProSe-enabled.
There may be two deployment scenarios: general (or non-public safety) and public safety specific. General scenarios for in network (NW) coverage may be applicable for both public safety and non-public safety. In NW coverage can refer to a case in which a UE can communicate with the cellular network. Furthermore, there may be an additional public safety specific scenario for out of NW coverage and/or partial NW coverage cases. Out of NW coverage can refer to a case in which a UE cannot communicate with the cellular network and partial NW coverage can refer to a case in which not all UEs involved in the same D2D communication group (the group could include two or more UEs) have direct communication with NW.
UEs can be grouped to D2D-passive and D2D-active UEs. The group of D2D-passive UEs can include UEs that are in a D2D discovery state. These UEs are just trying to discover other D2D UEs or be discovered and do not otherwise participate to any D2D communication. Some of the D2D UEs may have proceeded to a state of active D2D communication with another UE. These UEs are in D2D-active state. The D2D-active state could typically also cover UEs with durations when the D2D communication has ceased temporarily.
Resource sharing among D2D pairs with ongoing communication can be based on contention or allocation. Allocation based systems are discussed below. Resource allocation can happen under the network control or autonomously within the group of devices in D2D communication.
In case of the general scenarios with network coverage, one way of network controlled resource allocation is that UE reports the discovered UEs to network, and then the network allocates D2D resources based on the reported information.
FIG. 1 illustrates an example of D2D communication set up procedure. As shown in FIG. 1, at 0 the UE1 110 may perform a D2D discovery procedure to discover other UEs 120 connected to eNB(s)/network 130. At 1, UE1 110 can send, to the eNB(s)/network 130 a proximity communication request with discovered UEs. Then, at 2, the eNB(s)/network 130 can identify UEs that are in active state.
At 3, the eNB(s)/network 130 can identify a possible reusable resource based on the identified UEs in active state. Then, at 4, the eNB(s)/network 130 can send an identification of the allocated resource to UE1 110 in a proximity communication response. Finally, at 5, UE1 110 can start D2D communication using the allocated resource, with one or more the other UEs 120.
This method involves potentially heavy signaling overhead and increased complexity when a huge number of devices is discovered in step 0 and reported in step 1, which may also lead to other issues, such as latency in link establishment during the eNB processing. This approach does not limit the reporting to only UEs in the D2D-active state, such as UEs that are important to be taken into account for D2D resource allocation.
In case of autonomous D2D resource allocation, one UE or multiple UEs may take the role of “master” and arrange resource allocations for D2D communication to avoid interference between neighboring D2D pairs/groups. In this case, it is necessary for a UE to check with the discovered UEs about the occupied resources. If there is no information about the D2D states of the discovered UEs, the UE has to check with all the discovered UEs. However, when the UE has the information during discovery phase, the number of devices to check can be reduced significantly.
FIG. 2 illustrates a comparison in cases between checking all discovered UEs and checking selected discovered UEs. As can be seen, checking a selected subset may reduce the checking burden.
As shown in FIG. 2, if there is no way for UE1 to know the other UEs' D2D states, UE1 needs to check the resource use with all the discovered UEs, for example, UE2, UE3 and the D2D clusters #1 and #2. If cluster #1 is known not to be in the D2D-active state, there is no need for UE1 to check the resource use with cluster #1. This is just one example, and the situation may involve many more UEs in a practical case.